Fault Diagnosis for Rotor Cage of Induction Motor under Inverter Supply Condition

The frequency conversion technique is widely used in each cortrol field,and people pay more and more attention to the electromagnetic interference problem caused by rapid switch-on and switch-off of semiconductor switches in inverters.This paper analyzes the stator current harmonic of induction motor and electromagnetic interference problem under inverter supply condition,and proposes the effective methods for reducing interference in the measure circuit.Based on this,the method of time-varying frequency spectrum are applied to realize the diagnosis of broken rotor bars .